You’re standing in a dimly lit fitting room, or perhaps you’re unboxing a package at home after a week of anticipation. You pull on a brand-new swimsuit, and in the mirror, it looks great. But a nagging thought lingers in the back of your mind. You remember that one bikini from two summers ago—the one that started sagging at the seat after three trips to the ocean, or the expensive one-piece where the vibrant cobalt turned into a dull, muddy grey after a few hours in a chlorinated pool. We have all been there, and frankly, it is frustrating to…